In-plane And Out-of-plane Mechanical Properties Of Reinforced Masonry Cavity Wall

Complex energy-saving wall is an important popularized new type energy-saving wall in China, which has been used in Northern China. When pushing forward the work on building energy conservation to hot summer and cold winter zone, it is important to make more research on the complex energy-saving wall and broaden its application range. In-plane and out-of-plane mechanical properties of masonry cavity shear wall have been researched in this paper with financial support from Changsha New Wall Material Office.Through the experiments of 6 compressive specimens, failure pattern, cracking load, ultimate capacity and deformation capacity of concrete block masonry using lime mortar were analyzed. It was shown that the ratio of cracking load to ultimate load was small. The vertical mortar joint cracked and the mortar in horizontal mortar joint dropped when the specimens were destroyed.A formula is provided to calculate the compressive capacity of concrete block masonry when the mortar strength is very low. The results showed that the contribution of mortar to compressive capacity of concrete block masonry cannot be neglected.Through the experiments of 12 shear specimens, failure pattern, cracking load and ultimate capacity of concrete block masonry using lime mortar were analyzed. Based on an overall consideration of the material strength of core column concrete and mortar, the block type, two formulas were put forward to calculate the shear capacity of concrete block masonry using lime mortar and normal concrete block masonry. The calculated values are in good agreement with the test results. The results indicate that mortar has a great influence on shear capacity of concrete block masonry when the strength of mortar is low, but the influence becomes gentle with the strength increasing of mortar.Two masonry cavity walls with aspect ratio of 0.88 and 1.17 were tested under horizontal low cyclic loading. The inner wythe was reinforced masonry shear wall while the outer wythe used shale brick. Rectangular ties and Z-ties were separately set between the wythe in the two cavity walls. Failure pattern, load-bearing, seismic behavior and the ability of working coordinately of two wythes were studied. Visible crossing cracks were discovered in the inner wythes of two cavity walls. Characteristic of bending failure appeared while aspect ratio increasing. Inner wythe and outer wythe had a fine ability of working coordinately. The results of steel tie bar stress analysis indicated that rectangular ties worked better than Z-ties. Based on an overall consideration of external masonry, block type, core column concrete, horizontal reinforcements and vertical reinforcements, a shear capacity formula of cavity walls was presented.Four masonry cavity walls with different types of steel tie bars were tested subjected to an out-of-plane loading. The results indicated that the steel tie bar made great contribution to the out-of-plane bearing capacity of outer wythe. At a pressure of 5.95kN/m2, the outer wythes were in elastic stage. Based on the test result, the wind load-bearing capacity of outer wythes of a 20 stories building is sufficient. Even if the basic wind pressure has reached 0.6kN/m2, the outer wythes are safe.